Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. For example, Spinal Cord Stimulation (SCS) techniques, which directly stimulate the spinal cord tissue of the patient, have been accepted as a therapeutic modality for the treatment of chronic neuropathic pain syndromes. The application of spinal cord stimulation has expanded to include additional applications, such as angina pectoralis, peripheral vascular disease, and incontinence, among others. Spinal cord stimulation is also a promising option for patients suffering from neuro-motor disorders, such as Parkinson's Disease, Dystonia and essential tremor.
An implantable SCS system typically includes electrode-carrying stimulation leads and neurostimulator. The stimulation leads are implanted at a stimulation site in proximity to the spinal cord tissue of the patient. The neurostimulator implanted remotely from the stimulation site, but coupled either directly to the stimulation lead(s) or indirectly to the stimulation lead(s) via a lead extension. The neurostimulation system may further include a handheld patient programmer to instruct the neurostimulator remotely for generating electrical stimulation pulses in accordance with selected stimulation parameters. The handheld patient programmer may, itself, be programmed by a technician attending the patient, for example, by using a Clinician's Programmer (CP), which typically includes a general purpose computer, such as a laptop, desktop, tablet computer or any other suitable computer having a programming software package installed thereon.
Thus, applied programmed electrical pulses can be delivered from the neurostimulator to the stimulation lead(s) to stimulate or activate a volume of the spinal cord tissue. Specifically, electrical stimulation energy conveyed to the electrodes creates an electrical field, which when strong enough, depolarizes (or “stimulates”) the neural fibers within the spinal cord beyond a threshold level. As a result, the firing of action potentials (APs) is induced that propagate along the neural fibers to provide the desired efficacious therapy to the patient.
Traditionally, a combination of such neurostimulation therapy and pharmacological therapy is prescribed for delivering fast relief to or against certain chronic diseases or disorders in a patient. The effectiveness of the pharmacological therapy changes during its therapeutic window. As a result, to maintain a positive net effect of neurostimulation therapy and pharmacological therapy, the patient manually adjusts the applied level of electrical stimulation energy during the therapeutic window. Such adjustment may temporally differ relative to the changing effectiveness of the pharmacological therapy within its therapeutic window. Consequently, the action of neurostimulation therapy may become unsynchronized with that of the pharmacological therapy and may disturb the overall treatment regime.
Therefore, there exists a need for a solution for synchronizing electrical stimulation therapy with the changing effect of pharmacological therapy.